Plant are fine fish died suddenly

As you may know from other posts. I have had leeches for over a year. I bought some Gourami's hoping they would eat the leeches. I noticed for the first time that the leaches had laid eggs on the under side of a plant. I had tried to treat the leeches with clout and all it killed was my pond snails. These are plant leeches.
Now to what happened. I did my normal 50%WC it was only my week to do a lite vac. I have not gotten a lot of junk when I did my last deep vac except leeches. About 3hrs WC I noticed that several (20 or so) of the leeches were free swimming. They have not done this before. They would inch there way up the glass wall. About 20mins later my water was slightly cloudy and all the fish were at the top gasping for air. I moved them out of the tank and most died immediately. All I have left are a young oto and 4 nerites. I do not understand what happened. During the crisis I did another 50% wc. I also tested the water. it was 0,0,4+-. The plants are healthy this morning. Damn I miss my fish and don't understand what happened. I did all the things with treating the water as normal.
Now to my question. There are a few leeches that I see, Most are dead. Not sure when their eggs hatch. I thought to treat the tank with Fluke tabs thus trying to save my cycle. Or should I just tear it all down and sterilize it. I would have to see if I could get some mulm from someone. How long will a cycle live with out fish? Any Idea's what I should do next?

Lifetime Member

It is very sad that you lost your fish. I am so sorry. And it wasn't your fault, either.

If you didn't add any chemicals to the water then there was something in the replacement water that poisoned them. Maybe your water supplier added something?

Or maybe, a long shot but . . . if you used a container to transfer the new water from the faucet to the aquarium, perhaps it had something in it. I've had that happen, when my "aquarium only" bucket was used to wash the dog.

It is just frustrating. I plan on tearing down the tank and starting over. I am kind of afraid to keep the plants that are in there. Would PP kill all the leeches and their eggs? I hate that. I just got a ROAK of plants that I have soaking in Alum after they were in PP. I don't know how to keep the plants alive without a cycled tank. What can I do to keep the algae away and them alive. I can set this tank back up after I sterilize it but will the plants that are soaking be ok for awhile? How long is awhile?
I can try to borrow some mulm from someone in the Sacramento club.

Lifetime Member

Once you're done soaking, you might want to look at some of the fishless cycling methods. Depending on what's in your tap water and the soil you use, you probably have enough nutrients to keep the plants going for a while. If you have enough plants you might not even really have to fight with algae. Plant's don't necessarily "need" a cycled tank. One of the benefits of having the plants in the tank is that they will use the nutrients from the fish directly so you don't have as much left over to ramp up on your cycle. That said, you'd be wise to hold off on stocking your tank for a couple of weeks or so and then just slowly start adding the fish until you're back where you were before the deaths. I'd definitely rinse the plants a bit in fresh and treated water before adding them back to the tank. As long as they're still alive they should be able to recover.

You may want to check out my post. I had something similar happen and think I found out the problem. Sorry to hear about your loss, but as soon as you mentioned "water change" I knew. We would notice this more with EI dosing since we do up to 50% water changes:

That is very interesting. Never thought of increase use of hot water could be the problem. Our is super cold from the tap now.
I called the water company and they said that Saturday that put some things in the water which increased the PH a lot. I was also told that if I look on their web site they tell us a couple of days ahead when they will be added chems. She did not know what they added and would get back to me. My PH is usually 6.5. I don't know if the PH is still high from there chems or from the fluke tabs I have been adding. Now reads 8 Did not think to check it the day of the death. Using EI now so I don't test as often. I bet a large PH change all at once could kill.

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